July 18, 2018

Topanga’s Turtles Surviving the Drought with a Little Help



Topanga’s Turtles Surviving the Drought with a Little Help

Seen above is #37, a female pond turtle who is missing right front and back legs, enjoying the pool.

Western pond turtles are the only native turtle in Southern California.

The combination of habitat loss, increased predation and edge effects associated with fuel modification and other development intrusions into the wildlands has resulted in a marked decrease in western pond turtle populations.

In 1986, the Southwest Herpetological Society documented turtles in 30 locations throughout the Santa Monica Mountains. A study by the Resource Conservation District of the Santa Monica Mountains (RCDSMM) in 2009 found western pond turtles remaining in only eight of those locations, and just three locations had more than five individuals. The 300 tagged turtles studied since 2002 in Topanga are the only population remaining that has a balanced distribution of adult males, females and juveniles characteristic of a healthy population. For the past four years, the man-made pond that the turtles rely upon for food and mating has been totally dry. That means that more than 300 turtles have been competing for limited food resources in the small bathtub-size, groundwater-fed refugia pools.

In 2014, thirty RCDSMM Stream Team volunteers met each Friday from September to November to hand carry 200 gallons of water over half a mile to keep them filled. Despite this amazing effort, more than 50 turtles died of starvation and predation. By June 2015, even these pools were no longer viable. Hand carrying water each week for five months until the rains come was not a realistic option.

Rosi Dagit, RCDSMM Senior Conservation Biologist, worked with Tim Hovey of California Department of Fish and Wildlife to come up with a plan. Thanks to the generous permission of the Manzanita School and Cali-Camp property, one of the natural turtle pools was made available and the round up began. In June, the Stream Team collected 48 turtles from throughout the drainage and brought them to the sanctuary pool, where they could be fed and the water level could be maintained with a hose.

But turtles like to wander and aestivate under chaparral shrubs during the hot summer months and they can climb vertical sandstone cliffs. The challenge is to keep the turtles in the sanctuary pond and keep the predators like raccoons out. Contributions of design skills, construction skills, pond building skills and funds from the Southern California Wetlands Recovery Project, along with incredible donations from many individuals, have all come together to create a temporary sanctuary pool.

Topanga Cub Scout Pack 24 spent an afternoon stringing recycled water bottles on to a wire that is now hanging on the wall, preventing turtles from climbing out of the pool.

Local pond creator Don Hamburger donated native aquatic plants to help provide food and habitat. Daniel von Wetter strung a tarp to provide shade and the RCDSMM Stream Team built an electric fence to keep raccoons and other predators out.

Christine Light from the Behler Chelonian Center provided great direction on edible plants that we could incorporate into the landscape to help with diet and medical care. The good news is that the temporarily captive turtles are gaining weight in their new pools. We look forward to being able to release them back into the wild when the rains return.


Topanga’s Turtles Surviving the Drought with a Little Help

The pond for disabled turtles located at the RCDSMM headquarters in Topanga.

Sadly, in the roundup we also found three female turtles that had their legs bitten off by raccoons and thus will not survive in the wild. Thanks to funding support for materials from the Southern California Wetlands Recovery Project and many individual donations, these legless turtles have moved into the predator-proof handicapped turtle pool at the RCDSMM office, built with labor contributed by Maurice Bourget Construction.

This safe enclosure provides both aquatic and terrestrial habitat, allowing the injured turtles to recover. While we wish that these turtles were able to be truly wild, we hope that we are able to keep them well and happy to live out their lives in safety. Maybe we will even find them some male companionship?

Western pond turtles can live for 30-40 years, and become sexually mature in two to five years. More than half of our turtles are adults that are at least 12 years old. Many have already survived the 1993 wildfire, spent dry years aestivating under the chaparral shrubs, gorged on tadpoles and other goodies when the rains came and reproduced during the few wet years.

Many of the adults have shells damaged by run-ins with coyotes, raccoons, ravens, and dogs, to list just a few of their potential predators.

Mating takes place in the water, and females lay between four to 11 eggs in underground nests. The eggs incubate over the summer and babies hatch out in the fall, but don’t emerge from underground until the spring rains soften the earth. When no rains fall, the hard dry soil makes it very difficult for the babies to dig their way out.

Although Southern California has historically experienced multi-year droughts, the combination of the natural variation in precipitation, the subtle yet real increases in temperature and the competition for scarce water resources have all collided at the turtle pond. Climate change is real and the effects are hitting us now.

Climate models suggest that we could experience up to a 4-degree F increase in average temperature by 2050. Few individual turtles can make the physiological, behavioral or ecological adjustments needed to adapt to shifting climate impacts to their habitat that fast. If we need to recruit approximately 40 percent of the turtle hatchlings into the population in order to keep it healthy, and the on-going drought reduces the number of females laying eggs and the number of hatchlings surviving their first year, we are faced with few good solutions to keeping the population viable.

For now, we have managed to buy some time with our efforts to support the turtles through this summer. Hopefully the predicted El Niño will bring rains this winter to restore their wild habitat.

However, it is time for thoughtful conversations about how to develop a plan for responding effectively to the very real impacts facing our local flora and fauna. Tackling the effects of climate change one turtle pond at a time is daunting; not taking any action is unthinkable. n

The Resource Conservation District of the Santa Monica Mountains is located at 540 S. Topanga Canyon Blvd., Topanga 90290; (818) 597-8627.

For more information: Rosi Dagit, RCDSMM Senior Conservation Biologist,(310) 455-7528, rdagit@rcdsmm.org, or Clark Stevens, RCDSMM Executive Officer, (310) 614-6636, cstevens@rcdsmm.org.